1. Field of the Invention
The present invention relates to an apparatus for processing information such as words, figures and pictures.
2. Description of the Related art
An apparatus for processing words has been Known and practiced typically as a word processor. The Known word processor comprises a first memory for storing character information such as letters, numbers, marks and symbols, an input device for entering selection commands selecting the character information in accordance with a text to be composed, a display for reading letters, numbers, marks and symbols denoted by said selection commands out of said first memory and displaying the thus read out letters, numbers, marks and symbols, a second memory for storing text information composed of the selected letters, numbers, marks and symbols, and an output device for reading the text information out of said second memory as an output.
For the sake of simplicity, the letters, numbers, puntuation marks and other typographical symbols are sometimes called "characters".
In general, the first memory for storing the character information comprises a read only memory (ROM) in which a number of dot patterns representing various letters, numbers, marks and symbols have been previously stored. In general, these dot patterns are formed as standardized character style. The input device generally comprises a keyboard and a display device. The keyboard includes character keys such as letter keys, number keys, punctuation mark keys and other typographical symbol keys, and function keys such as return key, backspace key, repeat key, tab (tabulator) key, tab set ket, decimal tab key, alignment keys and control key. Sometimes use may be made of a device for entering hand-written characters or a device for entering speech information of an operator. The output device generally comprises a printer for forming hard prints. The output device may comprise a device for transmitting the text informastion over a transmission path as a data signal or a device for recording the text information on a record medium such as floppy disc and magnetic tape.
As explained above, in the known word processor, the character information has been previously stored as the characters having standardized style. Usually there is further provided a faculty for forming and registering special letters, marks and symbols formed by a user. This faculty is sometimes called the external-word registration. The external-word entered by the user is considered to be an additional word to the standardized charcters. Therefore, once a text has been formed by using the standardized and additional characters, any desired number of documents having the same content can obtained. In the other words, when the text information has been stored in the second memory the text can be respectedly read out and a plurality of documents composed of the same characters, numbers, punctuation marks and other symbols can be printed. This feature is very important for the word processor particularly in case of delivering a plurality of documents having the same content to different receivers. However, in the known word processor, it is impossible to distinguish the documents having the same content from one another unless each documents have respective addresses. Similarly it is impossible to distinguiush a plurality of documents having the same content which are printed by the same word processor on different days. In this manner, heretofore, a plurality of documents having the same content and printed by the word processor in accordance with the same text information stored in the second memory could not be distinguished from one another. This make it more difficult to protect proprietary information or secure secret documents. Therefore, when a document might be transferred to third parties such as competitors, other organizations, other political parties, newsmen, resporters and information collecting agents, or when a document is duplicated, it is quite difficult to find a rout through which the secret was leaked out. In general, in case of duplicating a secret document, any address thereon is hidden and thus it is hardly possible to identify an original document from which the duplicated copy is formed. In the modern information-oriented society, the divulgence of classified information has become a serious social problem and it has become much more important how to keep or manage the classified information. Nowadays, since there have been developed machines which can form a plurality of documents having the same text, there is a great chance that confidential documents might be leaked out. Therefore, there has been earnestly desired to develop a positive measure for avoiding the divulgency of confidential documents.